Dapoxetine

Identification

Name

Dapoxetine

Accession Number

DB04884

Type

Small Molecule

Groups

Investigational

Description

Dapoxetine is a selective serotonin reuptake inhibitor, for the treatment of premature ejaculation. In a phase II proof-of-concept study conducted by PPD, dapoxetine demonstrated a statistically significant increase in ejaculatory latency when compared to placebo. Alza submitted a NDA to the FDA for dapoxetine for the treatment of premature ejaculation in December 2004. In October 2005, the company received a FDA Non-Approvable letter from the FDA, at which time they planned to work with regulators to address outstanding questions.

Pharmacology

Indication

For the treatment of premature ejaculation.

Pharmacodynamics

Dapoxetine is a selective serotonin reuptake inhibitor currently undergoing trials through Alza (under license from GenuPro, a collaboration between Eli Lilly and PPD). Dapoxetine is a short-acting SSRI drug currently being considered for approval by the Food and Drug Administration (FDA) for the treatment of premature ejaculation in men, which would make it the first drug approved for such treatment. Despite two clinical trials finished in 2006, experts doubt it will be approved by the FDA soon because SSRIs come with undesirable side-effects after long-term use, such as psychiatric problems, dermatological reactions, increase in body weight, lower sex-drive, nausea, headache, upset stomach and weakness, thus not significantly outweighing the benefit of premature ejaculation medication versus the risks. By contrast with SSRIs approved for depression, which take 2 weeks or longer to reach steady-state concentration, dapoxetine has a unique pharmacokinetic profile, with a short time to maximum serum concentration (about 1 h) and rapid elimination (initial half-life of 1-2 h).

Mechanism of action

The drug's mechanism of action is thought to be related to inhibition of neuronal reuptake of serotonin and subsequent potentiation of serotonin activity. The central ejaculatory neural circuit comprises spinal and cerebral areas that form a highly interconnected network. The sympathetic, parasympathetic, and somatic spinal centers, under the influence of sensory genital and cerebral stimuli integrated and processed at the spinal cord level, act in synergy to command physiologic events occurring during ejaculation. Experimental evidence indicates that serotonin (5-HT), throughout brain descending pathways, exerts an inhibitory role on ejaculation. To date, three 5-HT receptor subtypes (5-HT(1A), 5-HT(1B), and 5-HT(2C)) have been postulated to mediate 5-HT's modulating activity on ejaculation.